Abstract:
High-intensity, low-frequency noise in modern helicopters and land vehicles degrades the communication reliability and endangers the hearing of the crew. Passive noise attenuation is not effective in terms of the performance/cost ratio in such environments. While active noise reduction (ANR) headsets that use analog feedback control have been commercially available for some time, this paper will focus on digital ANR hearing protector/headsets, which apply a feedforward control approach. A prototype ANR hearing protector has been developed in the laboratory using a floating-point digital signal processor (DSP) and an adaptive feedforward control algorithm. The ANR performance will be discussed based on recent experimental results measured on five human subjects in a reverberation chamber. For the experiments, 12 to 300-Hz broadband white noise and simulated helicopter noise were used. The results showed good control stability and active noise reduction performance.